1. Field of the Invention
The present invention relates to a cooling apparatus for cooling thick steel plate wherein the amount of water applied for cooling can be controlled in the width direction of the thick steel plate.
2. Description of the Prior Art
Considerable research has recently been devoted to the process for production of thick steel plate with the aim of developing a process which, through the combination of low temperature rolling and forced cooling, will make it possible to reduce the amount of alloying elements required in thick steel sheet production, to carry out various processes with smaller energy consumption and to develop new types of steel products. This research has already produced substantial results.
The cooling apparatuses developed for the process encompassing such a combination of steps have been aimed at making it possible to carry out the cooling operation in a simple manner, thereby overcoming the problem of insufficient cooling capacity posed by the conventional cooling bed, and at realizing an improvement in steel quality, more particularly, in realizing a remarkable enhancement of steel strength and toughness. It is a requirement of the cooling operation that the cooling be uniform in order to respond to the demand for higher steel quality. Also, it is a requirement of the steel plate that, following the completion of the cooling step, it should have a degree of flatness sufficient for it to be used immediately as a commercial product. This requirement derives from the need to save energy and reduce the number of production processes.
The inventors of the present invention have devoted themselves to the development of a cooling apparatus capable of providing the uniform cooling required to satisfy the aforesaid conditions. Through their study they found that no matter how perfectly a cooling apparatus is able to carry out uniform distribution of water, when a steel plate of large area is subjected to transient type cooling, a number of factors, including some intrinsic to the steel plate itself, act to obstruct uniform cooling. The main ones of these factors are listed below: